1. Field of the Invention
The present invention relates to a valve moving system of an over head valve engine, comprising a rocker arm chamber disposed between the cylinder head and head cover, a pair of rocker arms located in the rocker arm chamber, one rocker arm co-operating with an inlet valve and the corresponding push rod and another rocker arm co-operating with an exhaust valve and the corresponding push rod and, a pair of footing bolts of the rocker arms support of the knuckle type for supporting a rocker arm.
2. Prior Art
Almost all engines for general use, which are mounted with a fuel tank thereupon, have been employed side valve engines take a serious view of manufacturing cost.
However, a tendency that side valve engines are being taken over by over head valve engines take a more serious view of running cost has been found recently in this art.
In this trend, the serious problem to be solved is matching the engine with various machines. Indeed, the fact that the height of the over head valve engine is higher than that of the side valve engine is well known.
Therefore, it has become desirable to make the height of the over head valve engine as small as that of the side valve engine. To this end, on the one hand, the bottom of the fuel tank is recessed upwardly to locate the tank lower by housing the engine head in the recess, and on the other hand, the importance of attempts to decrease the total height of the cylinder head is increasing.
However, the known over head valve engine comprises intake and exhaust valves having stems standing vertically, and rocker arm supports of the knuckle type for simplifying the operating mechanism. In this practice, the stems are extruded from the upper wall of the cylinder head, and the tops of the footing bolt of the rocker arm supports are further extruded upwardly from them. Therefore, the head cover should be made in a deep box, and the overall height of the engine should be high at the depth of the head cover. The overall height of the engine mounted with a fuel tank thereupon is still taller, so that the it may depart from the scope of the recent requirement for minimization of the size of the engine in this art.
Moreover, the over head valve engine of known type is provided with a breather within the head cover. However, the location of the breather is limited to a small space which is formed between a vertical side wall of the head cover and the rocker arms. The width of the breather is also limited within the space between a pair of rocker arms. Therefore, the length of the path available in the cavity of the breather for blow-by gas induced therein is limited shorter, and the performance of the breather is not superior.